Vascular Pathology — MCQs

A 36-year-old woman presents with muscle pain, fever, and chronic sinusitis. Physical examination shows mucosal ulcerations of the nasopharynx. A biopsy from her nasopharynx reveals necrotizing vasculitis with chronic inflammatory cells and giant cells surrounding necrotic areas. The presence of which of the following autoantibodies would be most consistent with a diagnosis of Wegener's granulomatosis?

Q95Easy

What is the primary mechanism by which smoking accelerates vascular injury?

Q96Medium

Peripheral edema in congestive cardiac failure (CCF) is primarily due to which of the following mechanisms?

Q97Easy

Virchow's triad includes all except which of the following?

Q98Medium

Irreversible changes in myocardial infarction are typically seen after how much time?

Q99Easy

Weibel-Palade bodies are present in which of the following cells?

Q100Medium

Which anatomical site is least commonly affected by air embolism?

Vascular Pathology Indian Medical PG Practice Questions and MCQs

Question 91: Which of the following blood vessels is affected in hypersensitivity vasculitis?

A. Capillaries
B. Arterioles
C. Postcapillary venules (Correct Answer)
D. Medium sized vessels

Explanation: **Explanation:** **Hypersensitivity Vasculitis** (also known as Leukocytoclastic Vasculitis or Cutaneous Small Vessel Vasculitis) [2] is an immune-mediated inflammation of the small blood vessels [1]. 1. **Why Postcapillary Venules are correct:** The pathogenesis involves a **Type III Hypersensitivity reaction**, where circulating antigen-antibody (immune) complexes deposit in the vessel walls. This deposition occurs preferentially in the **postcapillary venules** [2] because these vessels have lower flow rates and increased permeability, making them the primary site for immune complex entrapment and subsequent complement activation. Histologically, this manifests as "leukocytoclasis" (nuclear debris from neutrophils). 2. **Why other options are incorrect:** * **Capillaries and Arterioles:** While these are "small vessels," they are less commonly the primary site of involvement compared to the postcapillary venules in this specific clinical entity. * **Medium-sized vessels:** These are affected in conditions like **Polyarteritis Nodosa (PAN)** or **Kawasaki disease**. Hypersensitivity vasculitis is strictly a "small vessel vasculitis" and does not involve muscular arteries. **High-Yield NEET-PG Pearls:** * **Clinical Presentation:** Typically presents as **palpable purpura**, most commonly on the lower extremities (dependent areas) [1]. * **Triggers:** Often induced by drugs (penicillin, sulfonamides), infections, or systemic diseases [1]. * **Histology:** Look for "nuclear dust" (leukocytoclasis), fibrinoid necrosis, and neutrophilic infiltration of the vessel wall [1]. * **Classification:** It is categorized under **Immune Complex Small Vessel Vasculitis** in the Chapel Hill Consensus Conference nomenclature. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 278-280. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 518-519.

Question 92: A patient presents with respiratory symptoms including cough and hemoptysis, along with glomerulonephritis. Serum c-ANCA levels are found to be elevated. What is the most likely diagnosis?

A. Goodpasture’s syndrome
B. Classic polyarteritis nodosa
C. Kawasaki’s syndrome
D. Wegener’s granulomatosis (Correct Answer)

Explanation: ### Explanation The correct answer is **Wegener’s granulomatosis** (now known as Granulomatosis with Polyangiitis or GPA). **1. Why Wegener’s Granulomatosis is Correct:** GPA is a small-vessel vasculitis characterized by a classic clinical triad: **upper/lower respiratory tract involvement** (cough, hemoptysis, sinusitis) and **renal involvement** (pauci-immune necrotizing glomerulonephritis) [1]. The hallmark laboratory finding is the presence of **c-ANCA** (cytoplasmic antineutrophil cytoplasmic antibodies), which target **Proteinase-3 (PR3)** [1]. The combination of hemoptysis (lung) and hematuria (kidney) with elevated c-ANCA is pathognomonic for this condition [1]. **2. Why the Other Options are Incorrect:** * **A. Goodpasture’s syndrome:** While it also presents with a "pulmonary-renal syndrome" (hemoptysis and glomerulonephritis), it is mediated by **anti-GBM antibodies** (Type II hypersensitivity), not ANCA [3]. It lacks upper respiratory involvement [2]. * **B. Classic polyarteritis nodosa (PAN):** This is a medium-vessel vasculitis. Crucially, PAN **spares the lungs** and is typically ANCA-negative [1]. It is strongly associated with Hepatitis B. * **C. Kawasaki’s syndrome:** This primarily affects children and involves medium-sized vessels (especially coronary arteries). Clinical features include "strawberry tongue," hand/foot edema, and fever, rather than glomerulonephritis or c-ANCA. **3. NEET-PG High-Yield Pearls:** * **The "C" Rule for Wegener's:** **C**-shaped distribution (Nasopharynx, Lungs, Kidneys), **c**-ANCA positive, and treated with **C**yclophosphamide. * **Microscopic Polyangiitis (MPA):** Similar to GPA but lacks granulomas and is typically **p-ANCA** (MPO) positive [4]. * **Histopathology:** GPA shows necrotizing granulomas and "geographic" necrosis. * **Churg-Strauss (EGPA):** Look for asthma, eosinophilia, and p-ANCA [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 519-520. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 322-323. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 537-538. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 536-537.

Question 93: Dissecting hematoma is a clinical complication occurring in which of the following conditions?

A. Turner's syndrome
B. Klinefelter's syndrome
C. Down syndrome
D. Marfan syndrome (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. Marfan syndrome** **Mechanism:** A **dissecting hematoma** (commonly known as aortic dissection) occurs when blood enters the media of the aortic wall through an intimal tear, creating a false lumen [2][3]. The most common underlying predisposing factor is **cystic medial necrosis** (degeneration of the tunica media) [2]. Marfan syndrome is an autosomal dominant disorder caused by a mutation in the **FBN1 gene**, which encodes **fibrillin-1**. This defect leads to weakened elastic fibers and excessive TGF-β signaling, resulting in structural weakness of the aortic root and media, making these patients highly susceptible to aortic dissection and aneurysms [1]. **Analysis of Incorrect Options:** * **A. Turner’s Syndrome:** While Turner’s syndrome is associated with cardiovascular issues like **coarctation of the aorta** and bicuspid aortic valve (which can increase dissection risk), Marfan syndrome is the classic, more direct association with cystic medial necrosis and dissecting hematoma in medical examinations. * **B. Klinefelter’s Syndrome (47, XXY):** This is characterized by testicular dysgenesis and infertility. It has no significant association with aortic wall pathology or dissecting hematomas. * **C. Down Syndrome (Trisomy 21):** The primary cardiac associations are **Endocardial Cushion Defects** (ASD/VSD). It does not predispose patients to aortic dissection. **NEET-PG High-Yield Pearls:** * **Most common cause of Aortic Dissection:** Hypertension (causes hyaline arteriolosclerosis of vasa vorum). * **Most common inherited cause:** Marfan syndrome [1]. * **Histology:** Look for "Cystic Medial Necrosis" (fragmentation of elastic tissue and accumulation of proteoglycans) [2]. * **Clinical Sign:** Sudden onset "tearing" chest pain radiating to the back [4]. * **Classification:** **Stanford Type A** involves the ascending aorta (surgical emergency); **Type B** involves only the descending aorta (medical management). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 511-512. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 272-273. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 512-513. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, p. 266.

Question 94: A 36-year-old woman presents with muscle pain, fever, and chronic sinusitis. Physical examination shows mucosal ulcerations of the nasopharynx. A biopsy from her nasopharynx reveals necrotizing vasculitis with chronic inflammatory cells and giant cells surrounding necrotic areas. The presence of which of the following autoantibodies would be most consistent with a diagnosis of Wegener's granulomatosis?

A. Antigliadin antibodies
B. Antinucleolar antibodies
C. Antineutrophil cytoplasmic antibodies (Correct Answer)
D. Antimitochondrial antibodies

Explanation: The clinical presentation of chronic sinusitis, nasopharyngeal ulcerations, and biopsy findings of necrotizing granulomatous vasculitis with giant cells [1] is classic for **Granulomatosis with Polyangiitis (GPA)**, formerly known as **Wegener’s granulomatosis**. **1. Why the Correct Answer is Right:** GPA is a small-vessel vasculitis characterized by a "triad" of involvement: upper respiratory tract, lower respiratory tract (lungs), and kidneys (glomerulonephritis) [1]. The hallmark laboratory marker for GPA is **Antineutrophil Cytoplasmic Antibodies (ANCA)**. Specifically, GPA is most strongly associated with **c-ANCA (cytoplasmic pattern)**, which targets the enzyme **Proteinase-3 (PR3)** [1]. In active systemic GPA, c-ANCA has a sensitivity of over 90%. **2. Why the Incorrect Options are Wrong:** * **Antigliadin antibodies (A):** These are associated with **Celiac disease**, an autoimmune-mediated enteropathy triggered by gluten. * **Antinucleolar antibodies (B):** These are a subtype of Antinuclear Antibodies (ANA) seen in systemic sclerosis (**Scleroderma**), particularly the diffuse form. * **Antimitochondrial antibodies (D):** This is the highly specific hallmark for **Primary Biliary Cholangitis (PBC)**. **3. NEET-PG High-Yield Pearls:** * **GPA Triad:** Nasopharynx (saddle nose deformity), Lungs (hemoptysis/cavitation), and Kidney (RPGN/Crescentic GN) [1]. * **Microscopic Polyangiitis (MPA) vs. GPA:** MPA lacks granulomas and is associated with **p-ANCA (anti-MPO)**. * **Churg-Strauss (EGPA):** Characterized by asthma, eosinophilia, and p-ANCA. * **Treatment:** The standard induction therapy for GPA involves **Cyclophosphamide** or Rituximab combined with corticosteroids. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 519-520.

Question 95: What is the primary mechanism by which smoking accelerates vascular injury?

A. Retention of sodium
B. Increased aldosterone production
C. Promoting endothelial dysfunction (Correct Answer)
D. Increasing plasma catecholamines

Explanation: **Explanation:** **Correct Answer: C. Promoting endothelial dysfunction** Smoking is a major risk factor for atherosclerosis [1]. The primary mechanism involves the induction of **oxidative stress** via reactive oxygen species (ROS) present in cigarette smoke. These free radicals reduce the bioavailability of **Nitric Oxide (NO)**, a potent vasodilator and antithrombotic molecule. This leads to **endothelial dysfunction**, characterized by increased vascular permeability, enhanced leukocyte adhesion (via VCAM-1), and a pro-thrombotic state [1]. This dysfunction is the "initiating hit" in the Response-to-Injury hypothesis of atherosclerosis [1]. **Why other options are incorrect:** * **A & B (Retention of sodium / Increased aldosterone):** While chronic smoking can influence the Renin-Angiotensin-Aldosterone System (RAAS) over time, these are indirect effects related to secondary hypertension rather than the primary mechanism of direct vascular wall injury. * **D (Increasing plasma catecholamines):** Smoking does trigger a sympathetic surge (increasing heart rate and blood pressure), but this hemodynamic stress is secondary to the direct biochemical damage caused to the endothelium by toxins like nicotine and acrolein. **High-Yield Clinical Pearls for NEET-PG:** * **Atherosclerosis Hallmark:** The earliest visible lesion is the **Fatty Streak**, but the functional precursor is always **Endothelial Dysfunction** [1]. * **Synergistic Risk:** Smoking combined with hypertension or hyperlipidemia increases the risk of Ischemic Heart Disease (IHD) multiplicatively, not just additively. * **Buerger Disease (Thromboangiitis Obliterans):** A high-yield vasculitis exclusively linked to heavy smoking; the primary treatment is absolute smoking cessation. * **Key Mediator:** Decreased **eNOS (endothelial Nitric Oxide Synthase)** activity is a specific biochemical marker of smoking-induced damage. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 502-503.

Question 96: Peripheral edema in congestive cardiac failure (CCF) is primarily due to which of the following mechanisms?

A. Increased sympathetic tone
B. Atrial natriuretic peptide (ANP) release
C. Increased hydrostatic pressure (Correct Answer)
D. Pulmonary hypertension

Explanation: **Explanation:** The primary mechanism of peripheral edema in Congestive Cardiac Failure (CCF) is an **increase in capillary hydrostatic pressure** [1]. In CCF, the heart’s pumping capacity is impaired, leading to venous congestion [1]. This "back-up" of blood increases the pressure within the systemic venous system, which is transmitted to the capillaries [1]. According to Starling’s Law, elevated hydrostatic pressure forces fluid out of the vascular compartment into the interstitial space, resulting in dependent edema (typically in the ankles and pretibial region). **Analysis of Options:** * **Option A (Increased sympathetic tone):** While CCF triggers sympathetic activation to maintain cardiac output, this leads to vasoconstriction and tachycardia rather than being the direct cause of fluid extravasation. * **Option B (Atrial natriuretic peptide):** ANP is released in response to atrial stretch. It actually promotes diuresis and vasodilation to *reduce* fluid volume; thus, it opposes edema formation. * **Option D (Pulmonary hypertension):** This primarily leads to right-sided heart failure. While it can eventually cause peripheral edema via systemic venous congestion, the *proximate* physiological mechanism remains increased hydrostatic pressure. **High-Yield Clinical Pearls for NEET-PG:** * **Secondary Hyperaldosteronism:** In CCF, decreased cardiac output reduces renal perfusion, activating the **Renin-Angiotensin-Aldosterone System (RAAS)**. This leads to salt and water retention, further increasing hydrostatic pressure and worsening edema [1]. * **Edema Types:** Edema in CCF is **pitting** in nature. * **Nutmeg Liver:** Chronic passive congestion of the liver due to right-sided heart failure leads to a characteristic "nutmeg" appearance (centrilobular necrosis). * **Starling Forces:** Remember that edema is caused by: ↑ Hydrostatic pressure, ↓ Plasma oncotic pressure (e.g., Nephrotic syndrome), ↑ Capillary permeability (e.g., Inflammation), or Lymphatic obstruction [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 124-126.

Question 97: Virchow's triad includes all except which of the following?

A. Vessel wall endothelial injury
B. Thrombus formation
C. Local blood stasis
D. Intimal tear (Correct Answer)

Explanation: **Explanation:** **Virchow’s Triad** describes the three primary categories of factors that contribute to **thrombogenesis** (the formation of a thrombus) [1]. According to this principle, the integrity of the vascular system depends on a balance between these three components: 1. **Endothelial Injury (Option A):** This is the most important factor [1]. Damage to the vessel wall exposes subendothelial collagen and tissue factor, triggering platelet adhesion and the coagulation cascade [2]. 2. **Alterations in Normal Blood Flow (Option C):** This includes **stasis** (slow flow, common in veins) or **turbulence** (disrupted flow, common in arteries) [1]. Both prevent the dilution of clotting factors and promote endothelial activation [3]. 3. **Hypercoagulability:** An alteration in blood constituents (e.g., Factor V Leiden, malignancy) that increases the tendency of blood to clot [3]. **Why "Intimal Tear" is the Correct Answer:** While an **intimal tear** (Option D) can *cause* endothelial injury, it is a specific pathological event (often associated with aortic dissection) rather than a primary category of Virchow’s Triad. **Thrombus formation** (Option B) is the *result* of the triad, not a component of the triad itself. However, in the context of standard medical examinations, "Intimal tear" is considered the "odd one out" as it is a subset of injury, whereas the triad refers to the broad physiological categories. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of arterial thrombi:** Endothelial injury (e.g., atherosclerosis). * **Most common cause of venous thrombi (Phlebothrombosis):** Stasis and Hypercoagulability. * **Lines of Zahn:** Microscopic laminations (pale platelet/fibrin layers vs. dark RBC layers) that signify a thrombus formed in flowing blood, helping distinguish a pre-mortem thrombus from a post-mortem clot. * **Trousseau Sign:** Migratory thrombophlebitis associated with visceral malignancies (e.g., pancreatic cancer), illustrating the "Hypercoagulability" arm of the triad. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 132-133. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 142-143. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 136-137.

Question 98: Irreversible changes in myocardial infarction are typically seen after how much time?

A. A few seconds
B. 10 minutes
C. 20 minutes (Correct Answer)
D. 40 minutes

Explanation: **Explanation:** The transition from reversible to irreversible cell injury in myocardial infarction (MI) is a critical time-dependent process. **Why 20 minutes is correct:** When coronary blood flow is obstructed, myocardial cells immediately switch to anaerobic metabolism. However, they can only tolerate severe ischemia for a limited window. **Irreversible injury (necrosis)** typically begins after **20 to 40 minutes** of persistent ischemia [1]. During this period, the sarcolemmal membrane is breached, and intracellular enzymes (like Troponins and CK-MB) begin to leak into the interstitium. This 20-minute mark represents the "point of no return" where cell death (coagulative necrosis) becomes inevitable. **Analysis of Incorrect Options:** * **A. A few seconds:** Within 0–2 minutes, ATP levels drop and contractility ceases (functional failure), but these changes are entirely **reversible** if perfusion is restored [1]. * **B. 10 minutes:** At this stage, the myocardium remains in a state of reversible injury. While ultrastructural changes like mitochondrial swelling occur, the cells are still viable [1]. * **D. 40 minutes:** While necrosis continues to progress at 40 minutes, the *initial* onset of irreversible damage is established by the 20-minute threshold [1]. **High-Yield Clinical Pearls for NEET-PG:** * **First 0–2 minutes:** Loss of contractility (Reversible) [1]. * **20–40 minutes:** Irreversible injury/Necrosis begins [1]. * **2–4 hours:** First time CK-MB/Troponins can be detected in blood. * **4–12 hours:** Earliest light microscopic change (Wavy fibers) [1]. * **Gross Change:** The first visible gross change is **mottling**, seen between 12–24 hours (Triphenyl Tetrazolium Chloride/TTC stain can detect it earlier as a "pale area") [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 548-556.

Question 99: Weibel-Palade bodies are present in which of the following cells?

A. Vascular endothelial cells (Correct Answer)
B. Warthin Finkeldey cells
C. Leydig cells
D. Dendritic cells

Explanation: **Explanation:** **Vascular endothelial cells** are the correct answer because **Weibel-Palade bodies** are the characteristic storage organelles found exclusively in the cytoplasm of these cells [2]. They are rod-shaped, membrane-bound structures that play a critical role in hemostasis and inflammation. They primarily store and release two key molecules: 1. **von Willebrand Factor (vWF):** Essential for platelet adhesion to the subendothelium [1]. 2. **P-selectin:** A cell adhesion molecule that mediates the rolling of leukocytes during the inflammatory response [2]. **Analysis of Incorrect Options:** * **Warthin-Finkeldey cells:** These are multinucleated giant cells with eosinophilic nuclear and cytoplasmic inclusions, classically seen in the lymphoid tissue of patients with **Measles**. * **Leydig cells:** Found in the interstitium of the testes, these cells produce testosterone. Their characteristic histological feature is the **Reinke crystal** (rod-shaped cytoplasmic inclusions). * **Dendritic cells:** These are professional antigen-presenting cells. While they have specialized structures, they do not contain Weibel-Palade bodies. (Note: Birbeck granules are specific to Langerhans cells, a type of dendritic cell). **High-Yield Clinical Pearls for NEET-PG:** * **Marker Identification:** Weibel-Palade bodies are the ultrastructural hallmark of endothelial cells [2]. In immunohistochemistry, **CD31** and **vWF (Factor VIII-related antigen)** are used as markers for vascular tumors (e.g., Angiosarcoma). * **Location:** They are most abundant in the endothelial cells of the aorta and smaller arteries but are also present in capillaries and endocardium. * **Deficiency:** A deficiency in the contents of these bodies (vWF) leads to **von Willebrand Disease**, the most common inherited bleeding disorder [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 581-582. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Migration in the tissues toward a chemotactic stimulus, pp. 86-87.

Question 100: Which anatomical site is least commonly affected by air embolism?

A. Liver (Correct Answer)
B. Kidney
C. Heart
D. Brain

Explanation: **Explanation:** Air embolism occurs when gas bubbles enter the vascular system, potentially obstructing blood flow and causing distal ischemia. The clinical impact depends on the volume of air and the specific organ involved. **Why Liver is the correct answer:** The **liver** is the least commonly affected organ because it possesses a **dual blood supply** (the portal vein and the hepatic artery) and a highly efficient **sinusoidal filtration system**. The hepatic sinusoids act as a vast capillary bed that can trap and dissipate small amounts of air without causing significant ischemic damage or clinical symptoms. Furthermore, the liver is not a "terminal" organ in the context of systemic arterial air distribution as frequently as the brain or heart. **Analysis of Incorrect Options:** * **Brain (D):** Highly susceptible. Even minute amounts of air in the cerebral arterial circulation can lead to focal neurological deficits, seizures, or stroke (Cerebral Air Embolism) [1]. * **Heart (C):** Highly susceptible. Air in the coronary arteries causes acute myocardial infarction. Additionally, a large bolus of air in the right ventricle can create an "air lock," obstructing outflow to the lungs and causing sudden cardiac arrest. * **Kidney (B):** Frequently affected in systemic arterial embolism. The renal arteries are direct branches of the aorta, making the kidneys a common target for embolic phenomena, leading to renal infarction. **NEET-PG High-Yield Pearls:** * **Lethal Dose:** Approximately 100 ml of air is required to cause death in an adult. * **Positioning:** To manage venous air embolism, place the patient in the **Durant’s position** (Left lateral decubitus and Trendelenburg) to trap air in the right ventricular apex. * **Caisson Disease:** A chronic form of gas embolism characterized by ischemic necrosis (frequently in the femoral head, tibia, and humerus) [2]. * **Classic Triad:** Hypoxemia, neurological abnormalities, and petechial rash (more specific to fat embolism, but often compared). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 323-324. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 138-140.

Practice by Chapter

Atherosclerosis

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Hypertensive Vascular Disease

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Aneurysms and Dissection

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Vasculitis

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Venous Disease and Thrombosis

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Vascular Tumors

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Varicose Veins and Lymphatics

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Pathology of Vascular Interventions

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Vascular Diseases in Specific Organs

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Congenital Vascular Anomalies

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